Adding texture to acrylic paintings is easily done as there are so many mediums available for artists today. The photo shows a simple exercise to test different types of acrylic mediums. I used Golden Acrylic products for this and all of them dry transparent. In the top area, I used modeling paste, the middle area, I used tar medium. In the lower section I used pumice medium, crystalline medium, and the dark blue area is a fluid – poured medium (GAC 800). This medium was mixed with cobalt blue and is self settling as it puddles. The painting has a wash of cobalt blue mixed with burnt sienna and the greenish area was pthalo green. These Golden products are really expensive and I now make many of my own, homemade versions (except for tar medium and GAC 800). I will post some of my recipes at a later time on my web site.
Here are 2 samples of texture created with acrylic mediums. The crackle texture on the right is a homemade version using gesso and marble dust. How thick it is applied determines the size of the cracks. Golden makes this medium but it is expensive and I get the same results. The texture on the left is Golden molding paste medium (also, expensive). I now use some kind of painter’s putty.